AUTHOR=Yücel Ezgi I. , Sadeghi Roksana , Kartha Arathy , Montezuma Sandra Rocio , Dagnelie Gislin , Rokem Ariel , Boynton Geoffrey M. , Fine Ione , Beyeler Michael TITLE=Factors affecting two-point discrimination in Argus II patients JOURNAL=Frontiers in Neuroscience VOLUME=16 YEAR=2022 URL=https://www.frontiersin.org/journals/neuroscience/articles/10.3389/fnins.2022.901337 DOI=10.3389/fnins.2022.901337 ISSN=1662-453X ABSTRACT=

Two of the main obstacles to the development of epiretinal prosthesis technology are electrodes that require current amplitudes above safety limits to reliably elicit percepts, and a failure to consistently elicit pattern vision. Here, we explored the causes of high current amplitude thresholds and poor spatial resolution within the Argus II epiretinal implant. We measured current amplitude thresholds and two-point discrimination (the ability to determine whether one or two electrodes had been stimulated) in 3 blind participants implanted with Argus II devices. Our data and simulations show that axonal stimulation, lift and retinal damage all play a role in reducing performance in the Argus 2, by either limiting sensitivity and/or reducing spatial resolution. Understanding the relative role of these various factors will be critical for developing and surgically implanting devices that can successfully subserve pattern vision.